Typical resistance weld applications such as flat surface to flat surface geometry can be performed in atmosphere because the joining materials' geometry prevents air from interacting with the weld nugget during formation. Medical devices, however, commonly have a more complex geometry that does not protect the weld nugget during formation. Furthermore, material sets used in medical devices may often consist of mixed metallurgy and oxygen sensitive materials such as titanium, molybdenum (Moly), and nickel that may be deformed during the welding process. Therefore, there is a need in the art for improved welding methods and apparatuses.